Datasheet

LTC3728
9
3728fg
PIN FUNCTIONS
INTV
CC
(Pin 21/Pin 20): Output of the Internal 5V Linear
Low Dropout Regulator and the EXTV
CC
Switch. The driver
and control circuits are powered from this voltage source.
Must be decoupled to power ground with a minimum of
4.7µF tantalum or other low ESR capacitor.
EXTV
CC
(Pin 22/Pin 21): External Power Input to an
Internal Switch Connected to INTV
CC
. This switch closes
and supplies V
CC
power, bypassing the internal low drop-
out regulator, whenever EXTV
CC
is higher than 4.7V. See
EXTV
CC
connection in Applications section. Do not exceed
7V on this pin.
BG1, BG2 (Pins 23, 19/Pins 22, 18): High Current Gate
Drives for Bottom (Synchronous) N-Channel MOSFETs.
Voltage swing at these pins is from ground to INTV
CC
.
V
IN
(Pin 24/Pin 23): Main Supply Pin. A bypass capaci-
tor should be tied between this pin and the signal ground
pin.
BOOST1, BOOST2 (Pins 25, 18/Pins 24, 17): Bootstrapped
Supplies to the Topside Floating Drivers. Capacitors
are connected between the boost and switch pins and
Schottky diodes are tied between the boost and INTV
CC
pins. Voltage swing at the boost pins is from INTV
CC
to
(V
IN
+ INTV
CC
).
SW1, SW2 (Pins 26, 17/Pins 25, 15): Switch Node
Connections to Inductors. Voltage swing at these pins
is from a Schottky diode (external) voltage drop below
ground to V
IN
.
TG1, TG2 (Pins 27, 16/Pins 26, 14): High Current Gate
Drives for Top N-Channel MOSFETs. These are the out-
puts of fl oating drivers with a voltage swing equal to
INTV
CC
– 0.5V superimposed on the switch node voltage
SW.
PGOOD (Pin 28/Pin 27): Open-Drain Logic Output. PGOOD
is pulled to ground when the voltage on either V
OSENSE
pin is not within ±7.5% of its set point.
Exposed Pad (Pin 33) SGND: The Exposed Pad must be
soldered to PCB ground for electrical contact and rated
thermal performance.